An imaging device includes: an imaging element that outputs an image signal in a nondestructive manner; an image processor that performs predetermined processing on the outputted image signal to generate image data; and a controller that controls the image processor. Under control of the controller, the image processor reads out image signals from the imaging element a plurality of times within one exposure period, calculates a target gain value based on a target level and an added signal, and multiples the added signal by the target gain value to generate the image data. The target level is calculated based on a signal level of a last read-out image signal in one exposure period. The added signal being obtained by adding up the image signals read out the plurality of times.
Legal claims defining the scope of protection, as filed with the USPTO.
1. An imaging device comprising: an image sensor that outputs an image signal in a nondestructive manner; an image processor that performs predetermined processing on the image signal generated by the image sensor to generate image data; and a control circuit that controls the image processor, wherein, under control of the control circuit, the image processor reads out image signals from the image sensor a plurality of times within one exposure period, calculates a target gain value based on a target level and an added signal, and multiplies the added signal by the target gain value to generate the image data, the target level being calculated based on a signal level of a last read-out image signal in the one exposure period, the added signal being obtained by adding up the image signals read out the plurality of times.
2. The imaging device according to claim 1 , wherein the image processor reads out each of the image signals at a timing obtained by equally dividing the one exposure period.
3. The imaging device according to claim 1 , wherein assuming that the one exposure period is represented by L, the image processor reads out the image signals at a plurality of times in a period equal to or longer than L/2 of the one exposure period.
4. The imaging device according to claim 3 , wherein assuming that a read-out period for reading each of the image signals is represented by Tr, the image processor sets a last read-out timing in the number of times of reading out the image signals in the one exposure period as a last time point in the one exposure period, and sets a read-out timing other than the last read-out timing to fall within a period equal to or longer than L/2 of the one exposure period and less than L−Tr.
5. The imaging device according to claim 1 , wherein the image processor determines the number of times of reading out the image signals in a current exposure period based on the target gain value previously calculated.
6. The imaging device according to claim 1 , wherein the image processor detects one of a moving object area and an area other than the moving object area in each of the image signals, and the added signal is obtained by adding up the image signals read out the plurality of times with respect to the area other than the moving object area.
7. The imaging device according to claim 6 , wherein the image processor subtracts a reference image signal from a last read-out image signal in the one exposure period, and subtracts a result of the subtraction from the reference image signal, to detect one of the moving object area and an area other than the moving object area, the reference image signal being an image signal read out before the last read-out image signal.
8. A camera comprising: the imaging device according to claim 1 ; and an optical system including at least one optical element that focuses external light on the image sensor.
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May 18, 2019
September 22, 2020
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